Using stimulus to convert coal to mesophase pitch and carbon fibers

ABSTRACT

A method for forming mesophase pitch can include applying a stimulus to a first amount of coal tar to form a first amount of mesophase pitch. The stimulus can include one or more of an electromagnetic field (“EMF”) or a magnetic field. The method can further include evaluating a characteristic of the first amount of mesophase pitch, changing a parameter of the stimulus in response to evaluating the characteristic of the first amount of mesophase pitch, and applying the stimulus exhibiting the changed parameters to a second amount of coal tar to form mesophase pitch.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/821,331 filed on Mar. 20, 2019, the disclosure of which isincorporated herein, in its entirety, by this reference.

FIELD

The described embodiments relate generally to carbon based processingmethods. More particularly, the present embodiments relate to systemsand methods for using stimulus (e.g., electromagnetic fields (EMF)and/or magnetic fields) to convert coal to mesophase pitch and carbonfibers.

BACKGROUND

As is well known, for example in U.S. Pat. No. 4,590,055, the carbonfibers currently produced and widely used are classified into twocategories according to the starting material, i.e. the PAN(polyacrylonitrile)-based carbon fibers prepared by the carbonization ofpolyacrylonitrile fibers and the pitch-based carbon fibers prepared frompitches of coal- or petroleum-origin.

Despite the advantages of the pitch-based carbon fibers due to theirinexpensiveness, the PAN-based carbon fibers occupy the major current ofthe industrial high-performance carbon fibers having high mechanicalstrength and high modulus suitable for reinforcing various compositematerials. This is partly due to the tensile strength of the pitch-basedcarbon fibers being industrially produced being relatively low andlimited to 200 kg/mm² or below.

Various attempts have been made to develop high-performance carbonfibers starting from inexpensive pitch compositions. The properties ofthe starting pitch is one of the most important factors for obtaininghigh-performance pitch-based carbon fibers. Recently, several proposalshave been made for preparing a pitch composition suitable for forminghigh-performance carbon fibers, including (a) a method in which aspecific condensed polycyclic aromatic compound is subjected to a heattreatment or treatment in hydrogen (see, for example, Japanese PatentPublication Nos. 45-28013 and 49-8634); (b) a method in which amesophase pitch is obtained by subjecting a tar or pitch of petroleumorigin to a first heat treatment in the presence of a Lewis acidcatalyst followed by a second heat treatment after removal of thecatalyst (see, for example, Japanese Patent Publication No. 53-7533);(c) a method in which a mesophase pitch having a desired mesophasecontent is obtained by the heat treatment of a pitch in an atmosphere ofa flowing inert gas or under a reduced pressure (see, for example,Japanese Patent Kokai Nos. 53-86717 and 53-86718); and (d) a method inwhich an optically isotropic pitch is subjected to a treatment with anorganic solvent, e.g. benzene, toluene, and heptane, and the insolublefraction is heated to form neomesophase (see, for example, Japanese Pat.Nos. Kokai 54-160427, 55-58287 and 55-130809).

Unfortunately, the above described methods are not effective enough toresult in a pitch composition suited for the formation ofhigh-performance carbon fibers having a tensile strength comparable tothe PAN-based carbon fibers. Therefore, the actual application of carbonfibers prepared from an isotropic pitch is limited to those fields inwhich particularly high tensile strength is not required, such asreinforcement in asbestos substitutes. The mesophase pitch produced insome of the above described methods are limited in practicalmanufacturing processes due to their relatively high viscosity and poorspinnability, causing a difficulty in melt spinning at an economicallyfeasible velocity. Consequently, it is desirable to provide a moreeconomical method for producing coal based mesophase pitch for theproduction of carbon fibers with sufficiently high tensile strength.

SUMMARY

Embodiments disclosed herein relate to processes of using at least onestimulus to synthesize mesophase pitch which can be used as acarbon-fiber precursor. The stimulus includes at least one of anelectromagnetic field (“EMF”) or a magnetic field. In one exampleprocess, coal tar is continuously provided and a stimulus is applied tothe coal tar to form the mesophase pitch from the coal tar. The stimulusapplied to the coal tar can exhibit various parameters to expose thecoal tar to various electric fields, magnetic field strengths, and/ormagnetic flux densities. In one embodiment, the resulting mesophasepitch can be spin-ready.

In one embodiment, a method is disclosed. The method includes providingcoal tar and applying at least one stimulus to the coal tar to formmesophase pitch. The at least one stimulus includes at least one of anelectromagnetic field (“EMF”) or a magnetic field.

In some embodiments of the method, providing the coal tar includesforming the coal tar by reducing the particle size of provided coal toform coal powder, sieving the coal powder, pyrolyzing the coal,extracting the coal tar from the pyrolyzed coal, and/or distilling thecoal tar to remove one or more contaminants therefrom.

In some embodiments of the method, the at least one stimulus includesthe EMF.

In some embodiments of the method, the EMF exhibits a wavelength ofabout 1 mm to about 1 m.

In some embodiments of the method, the EMF includes a pulsed EMF.

In some embodiments of the method, applying the EMF to the coal tarincludes applying an EMF exhibiting a first property to the coal tarand, after applying the EMF exhibiting the first property, applying anEMF exhibiting a second property that is different than the firstproperty. The first property and the second property are at least one ofthe wavelength or intensity of the EMF.

In some embodiments of the method, the at least one stimulus includesthe magnetic field.

In some embodiments of the method, applying the magnetic field to thecoal tar includes varying a magnetic field strength of the magneticfield.

In some embodiments of the method, applying the at least one stimulus tothe coal tar includes heating the coal tar to a temperature of about100° C. to about 300° C.

In some embodiments of the method, the method further includesevaluating one or more characteristics of the coal tar or the mesophasepitch and, responsive to evaluating the one or more characteristics ofthe coal tar or the mesophase pitch, changing one or more parameters ofthe at least one stimulus that is applied to the coal tar.

In some embodiments of the method, the method further include formingthe mesophase pitch into carbon fiber.

In some embodiments of the method, the method further includes airblowing the mesophase pitch.

In some embodiments of the method, the method further includessubjecting the mesophase pitch to a thermal process.

In one embodiment, a method is disclosed. The method includes evaluatingone or more characteristics of coal tar or coal used to form the coaltar. The method also includes, responsive to the evaluation, selectingone or more parameters of at least one stimulus that is to be applied tothe coal tar. The method further includes applying the at least onestimulus exhibiting the one or more parameters to the coal tar to formmesophase pitch. The at least one stimulus includes at least one of anEMF or a magnetic field.

In some embodiments of the method, the at least one stimulus includesEMF and selecting one or more parameters of the at least one stimulusincludes selecting at least one of a wavelength, an intensity, or modeof the EMF.

In some embodiments of the method, the EMF exhibits a wavelength ofabout 1 mm to about 1 m.

In some embodiments of the method, the at least one stimulus includes amagnetic field and selecting one or more parameters of the at least onestimulus includes selecting at least one of a magnetic field strength ormode of the magnetic field.

In one embodiment, a method is disclosed. The method includes providingcoal tar and applying at least one stimulus to the coal tar to formmesophase pitch. The at least one stimulus includes at least one of anEMF or a magnetic field. The method further includes evaluating one ormore characteristics of the mesophase pitch and, responsive to theevaluation, changing one or more parameters of the at least onestimulus. Additionally, the method includes applying the at least onestimulus exhibiting the one or more parameters to subsequently providedcoal tar.

In some embodiments of the method the at least one stimulus includes EMFand selecting one or more parameters of the at least one stimulusincludes selecting at least one of a wavelength, an intensity, or modeof the EMF.

In some embodiments of the method the at least one stimulus includes amagnetic field and selecting one or more parameters of the at least onestimulus includes selecting at least one of a magnetic field strength ormode of the magnetic field.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the present disclosure,wherein identical reference numerals refer to identical or similarelements or features in different views or embodiments shown in thedrawings.

FIG. 1 is a flow chart of a method of forming mesophase pitch from coal.

FIG. 2 is a flow chart of a method 200 of forming mesophase pitch fromcoal.

FIG. 3A shows a sample mass spectrograph of pitch formed from coal tarusing a process including the application of a stimulus to the coal tar.

FIG. 3B shows a sample mass spectrograph of pitch formed from coal tarusing a conventional thermal process.

DETAILED DESCRIPTION

Embodiments disclosed herein relate to processes of using at least onestimulus to synthesize mesophase pitch which can be used as acarbon-fiber precursor. The stimulus includes at least one of anelectromagnetic field (“EMF”) or a magnetic field. In one exampleprocess, coal tar is provided and a stimulus is applied to the coal tarto form the mesophase pitch from the coal tar. In some examples, heat orthermal energy can also be applied to the coal tar along with thestimulus. That is, in some examples, the stimulus can be applied to coaltar that has been heated to a desired temperature. The stimulus appliedto the coal tar can exhibit various parameters to expose the coal tar tovarious electric fields, magnetic field strengths, and/or magnetic fluxdensities. In one example, the resulting mesophase pitch can bespin-ready.

The exposure of the coal tar, or other coal-derived precursor materialsto a stimulus such as an electric field and/or magnetic field can allowfor the formation of pitch including desired carbon product precursors,such as one or more specific aromatic precursor chemicals, at relativelyhigh levels of purity at lower processing temperatures and/or reducedtimes as compared to convention thermally-based processes.Advantageously, the formation of pitch including desired precursormolecules at high levels of purity without the need for high temperatureor long processing times can enable the processes described herein to berun or performed in a continuous reactor, further decreasing the cost offorming mesophase pitch from coal and the carbon products derivedtherefrom.

In one embodiment, providing the coal tar includes forming the coal tarprior to applying the stimulus to the coal tar. Forming the coal tar caninclude one or more steps of preparing coal, pyrolyzing or otherwisemodifying the coal to form the coal tar, or distilling the coal tar toremove one or more impurities therefrom.

In one embodiment, after forming the mesophase pitch, the process canalso include forming the mesophase pitch into one or more carbonproducts, such as graphene, fullerene, diamond, and/or carbon fibers. Insome examples, forming the mesophase pitch into carbon fibers caninclude one or more of spinning the mesophase pitch into fibers,stabilizing the fibers, carbonizing the fibers, or graphitizing thefibers. In some examples, the mesophase pitch formed by the processesdescribed herein can be used as a precursor to form allotropes of carbonincluding covalently bonded monolayers of carbon atoms arranged inhexagonal or aromatic structures. In some examples, the mesophase pitchformed by the processes described herein can be used as a precursor toproduce carbon sheets that have delocalized sp² hybridized pi-bondingwithin the sheet. By applying a stimulus having desired parameters tocoal tar as described herein, mesophase pitch can be produced thatincludes properties that allow it to serve as a precursor for the easyand efficient formation of desired carbon products. As a result, themesophase pitch including the desired component molecules at desiredpurities can allow for the formation of carbon products with desiredproperties. For example, mesophase pitch formed from coal by theprocesses described herein can be used to produce graphene or othercarbon products that have thermal conductivities up to about 5300 W/m K,that have electrical conductivities similar to conductivities achievedwith electron tunneling, that have mechanical strengths over 100gigapascals (GPa), that have moduli over 2 terapascals (TPa), and thatcan exhibit up to 20% elongation.

In one embodiment, the process can further include evaluating a product.The product evaluated can include one or more of the provided coal, thecoal tar, the mesophase pitch, the carbon product, or any intermediateproduct formed during the processes disclosed herein. Evaluating theproduct can adjust the process. In one example, the parameters of thestimulus applied to the coal tar can be adjusted based on evaluating thecoal and/or coal tar in order to produce a mesophase pitch having adesired composition and/or purity. In some examples, the parameters ofthe stimulus can be selected to produce a mesophase pitch or othercarbon product precursor material that has a desired set of propertiesfor forming specific carbon products therefrom. In one example, theparameters of the stimulus can be adjusted based on evaluating themesophase pitch or the carbon product formed from the coal tar and astimulus having these adjusted parameters can be applied to subsequentlyprovided coal tar in a substantially continuous manner, such as in aplant based setting.

For example, the magnetic behavior of specific component molecules orchemicals, such as aromatic molecules that are desired for use in theformation of graphene, can be evaluated and parameters of the stimuluscan be selected to efficiently produce a mesophase pitch from coal taror other coal-derived material that includes these component moleculesor chemicals at relatively high levels of purity.

Without wishing to be bound by any one theory, it is believed that theapplication of a stimulus to coal tar or other coal-derived precursorscan influence the behavior of the coal tar during a pitch formationprocess as described herein. In the example of a stimulus including amagnetic field, the application of the magnetic field to the coal tarcan have a thermodynamic effect and can increase the Gibbs free energyavailable for polymerization reactions or other desired reactions thatoccur during pitch formation. Further, the magnetic field can increasethe effective pressure of the coal tar, increasing reaction speeds. TheZeeman effect can also include the bonding and crystal structure of themolecules formed during the conversion of coal tar to mesophase pitch.

FIG. 1 is a flow chart of a method 100 of forming mesophase pitch,according to one example. The mesophase pitch formed according to themethod 100 can be suitable for forming carbon fiber, graphene,fullerene, diamond, or other carbon products described herein. As shownin FIG. 1 , the method 100 includes act 102, which includes providingcoal tar. The method 100 also includes act 104, which includes applyingat least one stimulus to the coal tar to form the mesophase pitch.

Act 102 includes providing coal tar. In one embodiment, act 102 includesproviding pre-formed coal tar. In such one embodiment, the method 100does not include processing the coal tar and, instead, the method 100includes proceeding straight to act 104. In one embodiment, as discussedin more detail with regards to FIG. 2 , act 102 can include forming thecoal tar. In such one embodiment, the method 100 can include performingone or more processes to form the coal tar before proceeding to act 104.In some examples, act 102 can include providing coal, such as anthracitecoal and/or coal extracted from Wyoming's Powder River Basin.

Act 104 includes applying at least one stimulus to the coal tar to formthe mesophase pitch. The stimulus applied to the coal tar includes atleast one of EMF or a magnetic field. Applying the stimulus to the coaltar can increase the molecular weight of the coal tar (e.g., polymerizesthe coal tar) in a desired and controlled manner to form the mesophasepitch. The stimulus efficiently and economically synthesizes the coaltar into the mesophase pitch that can then be used in the production ofcarbon fibers. For example, the stimulus can minimize the overallprocessing cost by reducing processing times and temperatures requiredto form the mesophase pitch while assuring the mesophase pitch has thechemical and physical characteristics to produce desired carbonproducts, such as carbon fibers or graphene.

In some examples, the stimulus can be applied to coal tar that has beenheated to a desired temperature or range of temperatures. In someexamples, the coal tar or other coal-derived precursor can be heated toa temperature of at least about 30° C., at least about 40° C., at leastabout 50° C., at least about 60° C., at least about 70° C., at leastabout 80° C., at least about 90° C., at least about 100° C., at leastabout 110° C., at least about 120° C., at least about 130° C., at leastabout 140° C., at least about 150° C., at least about 160° C., at leastabout 170° C., at least about 180° C., at least about 190° C., at leastabout 200° C., at least about 210° C., at least about 220° C., at leastabout 230° C., at least about 240° C., at least about 250° C., at leastabout 260° C., at least about 270° C., at least about 280° C., at leastabout 290° C., at least about 300° C., at least about 325° C., at leastabout 350° C., at least about 375° C., at least about 400° C., or atleast about 500° C. or greater. In some examples, and as describedherein, the application of the stimulus to the coal tar can allow forthe formation of mesophase pitch having desired properties without theneed to heat the coal tar as much or as long as would be required inconventional processes.

In some examples, the application of the stimulus to the coal tar at act104 can be carried out in the presence of one or more catalysts,solvents, or other chemicals. That is, the coal tar can be combined ormixed with one or more catalysts or solvents and then the stimulus canbe applied to the mixture comprising the coal tar. In some examples, asolvent can include one or more of N-Methyl-2-pyrrolidone (NMP),quinoline, fluorinert FC-71, silicone oils, phthalates such as dioctylphthalate, syltherm 800, or any other suitable solvent or carrier.Additionally, in some examples, the coal tar can be combined with acatalyst that can enhance the effect of the stimulus on the coal tar andcan provide for more efficient converions into mesophase pitch havingdesired properties. In some examples, the catalyst can include a lewisacid. In some examples, such as where the stimulus includes a magneticfield, the catalyst can include one or more of a magnetic lewis acid ora non-magnetic lewis acid. In some examples, substantially any lewisacid can be used. In some examples, the lewis acid can include a metalchloride, such as iron chloride and/or aluminum chloride.

Act 104 can include positioning the coal tar in a chamber. The chambercan be formed from a closed container, an open container, or any otherdevice that can hold the coal tar. The chamber can include at least onestimulus source. The stimulus source can be disposed in the chamber. Inone embodiment, the stimulus source is an EMF source. The EMF source caninclude at least one black light, at least one curing lamp, at least onegermicidal lamp, at least one mercury vapor lamp, at least one halogenlamp, at least one high-intensity discharge lamp, at least onefluorescent lamp, at least one incandescent lamp, at least one laser, atleast one light emitting diode (LED), or any other suitable lightsource. In one embodiment, the stimulus source is a magnetic fieldsource. The magnetic field source can include a permanent magnet or,more preferrably, an electromagnet since the parameters of theelectromagnet can be easily changed.

In one embodiment, the chamber can include at least one agitatorconfigured to mix the coal tar. The agitator can ensure that the coaltar is exposed such that the coal tar is exposed equally orsubstantially equally to the stimulus. For example, the stimulus can beapplied preferentially to certain regions of the chamber relative toother regions of the chamber and/or the coal tar may not be perfectlypermeable to the stimulus (e.g., the coal tar absorbs, reflects, or isotherwise partially impermeable to the stimulus). The agitator ensuresthat the coal tar is substantially equally exposed to the stimulus, evenwhen the stimulus is applied preferentially to certain regions of thechamber and/or the coal tar is not perfectly permeable to the stimulus

In one embodiment, the stimulus applied to the coal tar is an EMF. TheEMF applied to the coal tar can exhibit a variety of parameters. Forexample, the parameters can include the wavelength of the EMF, theintensity of the EMF, the modes of the EMF, duration that the EMF isapplied to the coal tar, etc. The parameters of the EMF can affect howeffectively the EMF changes the coal tar to the mesophase pitch.

The wavelength of the EMF applied to the coal tar can be ultravioletlight. In one example, the wavelength of the EMF can be about 10 nm toabout 400 nm (ultraviolet light), such as in ranges of about 10 nm toabout 121 nm (extreme ultraviolet light), about 122 nm to about 200 nm(far ultraviolet light), about 200 nm to about 300 nm (middleultraviolet light), about 300 nm to about 400 nm (near ultravioletlight), about 100 nm to about 280 nm (hard ultraviolet light), about 280nm to about 315 nm (intermediate ultraviolet light), or about 315 nm toabout 400 nm (soft ultraviolet light). In one example, the wavelength ofthe EMF can be about 400 nm to about 700 nm (visible light) or about 700nm to about 1 mm (infrared light), such as in ranges of about 750 nm toabout 1.4 μm (near-infrared), about 1.4 μm to about 3 μm(short-wavelength infrared), about 3 μm to about 8 μm (mid-wavelengthinfrared), about 8 μm to about 15 μm (long-wavelength infrared), orabout 15 μm to about 1 mm (far infrared). In one example, the wavelengthof the EMF can be about 1 mm to about 1 m (microwave), such as in rangesof about 1 mm to about 10 mm, about 5 mm to about 50 mm, about 10 mm toabout 100 mm, about 50 mm to about 500 mm, or about 100 mm to about 1 m.

The wavelength of the EMF can be selected based on several factors. Inone example, the wavelength of the EMF can be selected based on whetherthe EMF is configured to heat the coal tar by having one or moreconstitutents of the coal tar absorb the EMF or be excited by the EMF.In one example, the wavelength of the EMF can be selected based onwhether the EMF is configured to cause a curing chemical reaction, achemical reaction caused by heating the coal tar, and/or a physicalreaction of one or more constitutents of the coal tar. In one example,the wavelength of the EMF can be selected based on one or morecharacteristics of the coal tar, such as the average molecular weight ofthe pitch present in the coal tar, the composition of the coal tar, thesource of the coal tar, etc. For instance, the coal tar can reactdifferently to different wavelengths of the EMF, depending on thecharacteristics of the coal tar. As such, the wavelength of the EMF canvary depending on the characteristics of the coal tar.

The intensity of the EMF applied to the coal tar can be about 100 μW/cm²or more, about 250 μW/cm² or more, about 500 μW/cm² or more, about 750μW/cm² or more, about 1 mW/cm² or more, about 2.5 mW/cm² or more, about5 mW/cm² or more, about 7.5 mW/cm² or more, about 10 mW/cm² or more,about 25 mW/cm² or more, about 50 mW/cm² or more, about 100 mW/cm² ormore, about 250 mW/cm² or more, about 500 mW/cm² or more, about 750mW/cm² or more, about 1 W/cm² or more, or in ranges of about 100 μW/cm²to about 500 μW/cm², about 250 μW/cm² to about 750 μW/cm², about 500μW/cm² to about 1 mW/cm², about 750 μW/cm² to about 2.5 mW/cm², about 1mW/cm² to about 5 mW/cm², about 2.5 mW/cm² to about 7.5 mW/cm², about 5mW/cm² to about 10 mW/cm², about 7.5 mW/cm² to about 25 mW/cm², about 10mW/cm² to about 50 mW/cm², about 25 mW/cm² to about 75 mW/cm², about 50mW/cm² to about 100 mW/cm², about 75 mW/cm² to about 250 mW/cm², about100 mW/cm² to about 500 mW/cm², about 250 mW/cm² to about 750 mW/cm², orabout 500 mW/cm² to about 1000 W/cm². The intensity of the EMF candetermine whether the coal tar converts into mesophase pitch or anothercompound. For example, an intensity of EMF too great can cause the coaltar to form ash while an intensity of the EMF too low can form mesophasepitch with poor qualities. Whether the intensity of the EMF is too greator too low can depend on the characteristics of the coal and thewavelength of the EMF. As such, the intensity of the EMF can be selectedbased on the characteristics of the coal tar and the intensity of theEMF.

The duration that the EMF is applied to the coal tar can be about 1second or greater, such as in ranges of about 1 second to about 1minute, about 30 seconds to about 5 minutes, about 1 minute to about 10minutes, about 5 minutes to about 25 minutes, about 20 minutes to about40 minutes, about 30 minutes to about 1 hour, about 40 minutes to about2 hours, about 1 hour to about 3 hours, about 2 hours to about 4 hours,about 3 hours to about 6 hours, about 4 hours to about 8 hours, about 6hours to about 12 hours, or greater than about 9 hours, or any desiredlength of time. The duration that the EMF is applied to the coal tar candepend on several factors. In one example, the duration that the EMF isapplied to the coal tar can be selected based on the wavelength of theEMF and/or the intensity of the EMF since how long it takes to convertat least most of the coal tar into mesophase pitch and/or incidentlyconvert some of the mesophase pitch into another compound (e.g., ash)depends on the wavelength and intensity of the EMF. In one example, theduration that the EMF is applied to the coal tar can depend on thecharacteristics of the coal tar since the characteristics of the coaltar affect how long it takes to convert at least most of the coal tarinto mesophase pitch and/or incidently convert some of the mesophasepitch into another compound. The duration that the EMF is applied to thecoal tar can depend on the amount of the coal tar exposed to the EMF,whereas increasing the quantity of the coal tar can increase theduration that the EMF is applied to the coal tar.

In one embodiment, the mode of the EMF applied to the coal tar can be apulsed EMF which can decrease the energy expended to convert the coaltar into mesophase pitch or non-pulsed (e.g., constant) EMF which canconvert the coal tar into mesophase pitch quicker than the pulsed EMF.In one embodiment, the mode of the EMF applied to the coal tar caninclude varying the wavelength of the EMF applied to the coal tar. Forexample, the EMF can initially exhibit a first wavelength and can thenbe changed to a second wavelength that is different than the firstwavelength. After the second wavelength, the EMF can change back to thefirst wavelength or a third wavelength that is different than the firstand second wavelengths. The first, second, and third wavelengths caninclude any of the wavelengths (or ranges of wavelengths) disclosedherein. Varying the wavelengths of the EMF can make converting the coaltar to the mesophase pitch quicker and/or more efficient. In oneexample, the first wavelength can more efficiently convert pure coal tarinto mesophase pitch while the second wavelength can more efficientlyconvert a mixture of coal tar and mesophase pitch into mesophase pitch.In one example, the different wavelengths can convert differentconstitutents of the coal tar into mesophase pitch. In one example, thefirst wavelength can be selected to convert the coal tar into mesophasepitch and the second wavelength can cause the mesophase pitch to exhibitcertain properties. In one embodiment, the mode of the EMF applied tothe coal tar can include varying the intensity of the coal tar. Forexample, the EMF can exhibit a first intensity followed by a secondintensity that is different than the first intensity and then,optionally, switch back to the first intensity or a third intensity thatis different than the first and second intensities. Similar to varyingthe wavelength of the EMF, varying the intensity of the EMF can allowfor the conversion of different constitutents of the coal tar intomesophase pitch, causing the mesophase to exhibit certain properties, orotherwise make converting the coal tar into mesophase pitch quicker andmore efficient.

In one embodiment, the stimulus applied to the coal tar is a magneticfield. The magnetic field applied to the coal tar can exhibit manyparameters. For example, the parameters can include the magnetic fieldstrength (i.e., the H-field), the modes of the magnetic field when themagnetic field source is an electromagnet, duration that the magneticfield is applied to the coal tar, etc. The parameters of the magneticfield can affect how effectively the magnetic field changes the coal tarto the mesophase pitch.

The magnetic field strength of the magnetic field applied to the coaltar can be about 5 milliteslas (“mT”) or greater, about 10 mT orgreater, about 50 mT or greater, about 100 mT or greater, about 200 mTor greater, about 500 mT or greater, about 1 tesla (“T”) or greater,about 2 T or greater, about 3 T or greater, about 4 T or greater, about5 T or greater, about 7.5 T or greater, about 10 T or greater, or inranges of about 5 mT to about 50 mT, about 10 mT to about 100 mT, about50 mT to about 200 mT, about 100 mT to about 500 mT, about 200 mT toabout 1 T, about 500 mT to about 2 T, about 1 T to about 3 T, about 2 Tto about 4 T, about 3 T to about 5 T, about 4 T to about 7.5 T, about 5T to about 10 T, or about 7.5 T to about 15 T. In some examples, themagnetic field strength can be about 1 T, about 2 T, about 3 T, about 4T, about 5 T, about 6 T, about 7 T, about 8 T, about 9 T, about 10 T,about 11 T, about 12 T, about 13 T, about 14 T, about 15 T, or about 20T, The magnetic field strength of the magnetic field can be selectedbased on several factors. In one example, the magnetic field strength ofthe magnetic field can be selected based on whether the magnetic fieldis configured to heat the coal tar, cause a curing chemical reaction,cause another type of chemical reaction, and/or cause a physicalreaction. In one example, the magnetic field strength of the magnet canbe selected based on one or more characteristics of the coal tar, suchas the average molecular weight of the pitch present in the coal tar,the composition of the coal tar, the source of the coal tar, etc. Forinstance, the coal tar can react differently to different magnetic fieldstrengths, depending on the characteristics of the coal tar.

When the magnetic field source is an electromagnet, the magnetic fieldcan exhibit one or more modes. In one embodiment, the mode of the magnetfield can include applying a constant magnetic field to the coal tar. Inone embodiment, the mode of the magnet field can include applying analternative magnetic field or a pulsed magnetic field. In oneembodiment, the mode of the magnetic field applied to the coal tar caninclude varying the magnetic field strength of the magnetic fieldapplied to the coal tar. For example, the magnetic field can initiallyexhibit a first magnetic field strength, and then can be changed to asecond magnetic field strength that is different than the first magneticfield strength. After the second magnetic field strength, the magneticfield can change back to the first magnetic field strength or to a thirdmagnetic field strength that is different than the first and secondmagnetic field strengths. The first, second, and possibly third magneticfield strengths can include any of the magnetic field strengths (orranges of magnetic field strengths) disclosed herein. Varying themagnetic field strength of the magnetic can make converting the coal tarto the mesophase pitch quicker and/or more efficient and can result inthe formation of mesophase pitch having a desired composition and/ordesired purity. In one example, the first magnetic field strength canmore efficiently convert pure coal tar into mesophase pitch while thesecond magnetic field strength can be more efficient convert a mixtureof coal tar and mesophase phase pitch into mesophase pitch. In oneexample, the different magnetic field strengths can convert differentconstitutents of the coal tar into mesophase pitch. In one example, thefirst magnetic field strength can be selected to convert the coal tarinto mesophase pitch and the second magnetic field strength can causethe mesophase pitch, and resulting products formed of the mesophasepitch, to exhibit certain properties.

The duration that the magnetic field is applied to the coal tar can beabout 1 second or greater, such as in ranges of about 1 second to about1 minute, about 30 seconds to about 5 minutes, about 1 minute to about10 minutes, about 5 minutes to about 25 minutes, about 20 minutes toabout 40 minutes, about 30 minutes to about 1 hour, about 40 minutes toabout 2 hours, about 1 hour to about 3 hours, about 2 hours to about 4hours, about 3 hours to about 6 hours, about 4 hours to about 8 hours,about 6 hours to about 12 hours, or greater than about 9 hours. Theduration that the magnetic field is applied to the coal tar can dependon several factors. In one example, the duration that the magnetic fieldis applied to the coal tar can be selected based on the magnetic fieldstrength. The duration of time necessary to convert at least most of thecoal tar into mesophase pitch and/or incidently convert some of themesophase pitch into another compound (e.g., ash) depends at leastpartially on the magnetic field strength. In one example, the durationthat the magnetic field is applied to the coal tar can depend on thecharacteristics of the coal tar since the characteristics of the coaltar affect how long it takes to convert at least most of the coal tarinto mesophase pitch and/or incidently convert some of the mesophasepitch into another compound. The duration that the magnetic field isapplied to the coal tar can depend on the amount of the coal tar exposedto the magnetic field, wherein increasing the quantity of the coal tarcan increase the duration that the magnetic field is applied to the coaltar.

In one embodiment, the stimulus applied to the coal tar includes both anEMF and a magnetic field. Applying both the EMF and the magnetic fieldto the coal tar can make the process more cost and/or energy efficient,decrease the time that the stimulus is applied to the coal tar, and/orform mesophase pitch exhibiting more beneficial properties if only oneof the EMF or the magnetic field is applied to the coal tar.

The temperature that the coal tar is heated to during act 104 can vary.Varying the temperature of the coal tar can allow act 104 to moreeffectively change the coal tar to mesophase pitch. For example, thecoal tar can be initially heated to a first temperature. The firsttemperature can include any of the temperatures disclosed herein. Thetemperature of the coal tar can subsequently be heated or cooled to asecond temperature that is different than the first temperature. Thesecond temperature can include any of the temperatures disclosed herein.Changing the temperature of the coal tar from the first temperature tothe second temperature can optimize the method 100. For example, aproduct of the method 100 can be evaluated. Act 104 can change thetemperature of the coal tar from the first temperature to the secondtemperature when, for instance, the evaluation determines that changingthe temperature of the coal tar can make act 104 more efficient orproduce better carbon fibers. It is noted that act 104 can includechanging the temperature of the coal tar between many temperatures,without limitation.

FIG. 2 is a flow chart of a method 200 of forming mesophase pitch,according to one embodiment. The mesophase pitch formed according to themethod 200 can be suitable for forming carbon fiber. Except as otherwisedisclosed, the method 200 is the same or substantially similar to any ofthe methods disclosed herein. For example, the method 200 can be thesame or substantially similar to the method 100 except that the act ofproviding the coal tar includes forming the coal tar. The method 200includes act 202, which recites “forming coal tar.” The method 200 alsoincludes act 204, which recites “applying at least one stimulus to thecoal tar to form the mesophase pitch.”

Act 202 can begin with subact 202 a, which recites “preparing the coal.”Subact 202 a can be followed by subact 202 b, which recites “formingcoal tar from the prepared coal.” Subact 202 b can be followed by subact202 c, which recites “distilling the coal tar.” The subacts included inact 202 are for illustration purposes. In some examples, one or more ofthe subacts 202 a, 202 b, and/or 202 c can be performed in a differentorder, eliminated, divided into additional subacts, modified,supplemented with other subacts, or combined into fewer subacts.

Subact 202 a includes preparing the coal. Preparing the coal includespreparing the coal to be transformed into coal tar. In one embodiment,subact 202 a can include reducing the particle size of the coal to forma coal powder. For example, subact 202 a can include reducing theparticle size of the coal so the coal exhibits a particles size about 1cm or less, about 7.5 mm or less, about 5 mm or less, about 2.5 mm orless, about 1 mm or less, about 750 μm or less, about 500 μm or less,about 250 μm or less, about 100 μm or less, about 75 μm or less, about50 μm or less, about 25 μm or less, about 10 μm or less, about 5 μm orless, or submicron. Reducing the particle size of the coal can decreasethe time and/or energy required to form the coal tar. In one embodiment,subact 202 a can include sieving the coal so the coal exhibits aselected particle size or less. Similar to reducing the size of thecoal, sieving the coal can ensure that the coal is free of largeparticles which can make forming the coal tar more difficult. In oneembodiment, subact 202 a includes drying the coal to remove moisturetherefrom since the moisture can interfere with the efficienttransformation of the coal into coal tar. In one embodiment, subact 202a includes a combination of the above embodiments.

In one embodiment, subact 202 a can be omitted from act 202. Forexample, subact 202 a can be omitted from act 202 when the coal providedalready exhibits a selected particles size and/or is dried.

Subact 202 b include forming the coal tar. The coal tar can be formedfrom the coal using any suitable method. In one embodiment, the coal taris formed from the coal using a pyrolysis technique. In such oneembodiment, the coal is heated, such as to a temperatures of about 1000°C. to about 2000° C. Heating the coal to such high temperatures canseparate the coal into different constituents, such as coke, coal tar,coal gas, and other organic substances. Subact 202 b includes collectingthe coal tar. Subact 202 b can also include collecting the otherconstituents of coal for other uses, thereby reducing waste and makingthe method 200 more efficient.

In one embodiment, subact 202 b can be omitted from act 202. Forexample, subact 202 b can be omitted from act 202 when the coal tar isprovided thereby negating the need to form the coal tar.

Subact 202 c includes distilling the coal tar. In one embodiment, subact202 c can first include drying the coal tar to remove water and othercontaminates therefrom. In one embodiment, subact 202 c includesfractionating the coal tar into different pitches for later conversioninto the mesophase pitch. For example, fractionating the coal tar caninclude fractionating the coal tar into naphthalene, anthracene, coaltar pitch, and other pitches. In such an example, at least the coal tarpitch is subsequently used to form mesophase pitch though, depending onthe parameters of the stimulus, other pitches can also be used. In oneembodiment, subact 202 c can include other methods of distilling thecoal tar, such as hot filtration of the coal tar to remove soluble orinsoluble impurities from the coal tar. In one embodiment, subact 202 ccan include a combination of the above embodiments. For instance, subact202 c can include drying the coal tar, fractionating the coal tar, andthen further filtrating the coal tar using the hot filtration technique.In one embodiment, subact 202 c can include collecting one or morecontaminates removed during the distilling process for other uses,thereby reducing waste and making the method 200 more efficient.

In one embodiment, subact 202 c can be omitted from act 202. Forexample, subact 202 c can be omitted from act 202 when determined thatthe coal tar (e.g., the coal tar formed during subact 202 b) need not bedistilled.

Following act 202, the method 200 includes act 204, which recites“applying at least one stimulus to the coal tar to form the mesophasepitch.” Act 204 is the same or substantially similar to the act 104 ofthe method 100.

In one embodiment, any of the processes disclosed herein can include,after forming the mesophase pitch, chemical and physical processing ofthe mesophase. The chemical and physical processing of the mesophasepitch can convert any remaining coal tar pitch that did not convert intomesophase pitch, improve the mesophase pitch, further increase themolecular weight of the mesophase pitch, functionalize or otherwisereact the mesophase pitch, and/or remove contaminants from the mesophasepitch.

In one embodiment, the chemical and physical processing of the mesophasepitch can include air blowing and/or thermal treatment. In one example,the resulting mesophase pitch can be air blown in the temperature rangeof about 200° C. to about 400° C., more preferably a temperature rangeof from about 250° C. to about 350° C., or more preferably in atemperature range of about 280° C. to about 320° C. Air blowingincreases the softening point of the mesophase pitch without destroyingits spinnability. In one example, a thermal treatment can be applied tothe mesophase pitch by heating the mesophase pitch to a temperature ofabout 300° C. to about 400° C., more preferably about 320° C. to about390° C., and most preferably about 350° C. to about 380° C. to increasethe softening point to approximately 280° C. Similar processes aredisclosed in the article Two-step chemical conversion of coal tar pitchto isotropic spinnable pitch, Fuel Processing Technology, Volume 104,December 2012, pages 155-159, the content of which is incorporated byreference, in its entirety.

In one embodiment, the chemical and physical processing of the mesophasepitch can include subjecting the mesophase pitch to a first heattreatment in the presence of a Lewis acid catalyst followed by a secondheat treatment after removal of the catalyst. Similar processes aredisclosed in Japanese Patent Publication No. 53-7533, the content ofwhich is incorporated by reference, in its entirety. In one embodiment,the chemical and physical processing of the mesophase pitch can includesubjecting the mesophase pitch to a heat treatment of a pitch in anatmosphere of a flowing inert gas or under a reduced pressure. Similarprocesses are disclosed in Japanese Patent Publication Nos. 53-86717 and53-86718, the content of which is incorporated by reference, in itsentirety. In one embodiment, the chemical and physical processing of themesophase pitch can include subjecting the mesophase pitch to atreatment with an organic solvent, e.g. benzene, toluene and heptane,and the insoluble fraction is heated to form mesophase. Similarprocesses are disclosed in Japanese Patent Publication Nos. 54-160427,55-58287 and 55-130809, the content of which is incorporated byreference, in its entirety.

In one embodiment, any of the processes disclosed herein can includeforming the mesophase pitch into carbon fibers. For example, forming themesophase pitch into carbon fibers can include one or more of spinningthe mesophase pitch into fibers (e.g., via a melt spin technique),stabilizing the mesophase pitch, graphitizing the mesophase fibers, orcarbonizing the mesophase fibers.

As previously discussed, the product formed during any of the methodsdisclosed herein can be subjected to evaluation. As used herein,evaluation, evaluated, etc. refers to analytical methods used to testone or more characteristics of the product. Evaluating the product candetermine whether one or more parameters of the stimulus applied to thecoal tar can need to be changed. In one example, evaluating a product isperformed before the stimulus is applied to the product (e.g., theprovided coal, the coal powder, the coal tar, and/or the distilled coaltar) and such evaluation can be to select the parameters of the stimulusapplied to the coal tar. In one example, evaluating a product isperformed after the stimulus is applied to the product (e.g., themesophase pitch, the spun fibers, and/or the carbon fibers) and such anevaluation can select parameters of the stimulus applied to subsequentlyprovided coal tar.

In one embodiment, the evaluation can include determining or predictingthe characteristics of the coal tar subject to the stimulus before thecoal tar is subjected to the stimulus. For example, as previouslydiscussed, certain parameters of the stimulus can be more efficient atconverting coal tar exhibiting certain characteristics to mesophasepitch than other parameters. The parameters of the stimulus can beselected based on the determined or predicted characteristics of thecoal tar. Further, the parameters of the stimulus can be changed whenthe evaluation determined or predicted that the characteristics of anewly provided coal tar is different than a previously provided coaltar. In one embodiment, the characteristics of the coal tar can bedetermined or predicted using a proximate and ultimate analysis. Theproximate and ultimate analysis can determine or predict the moisturecontent, sulfur content, calorific value, volatile matter content, fixedcarbon content, ash content, and elemental composition of the coal. Suchvalues can determine how the coal tar is formed (e.g., whether the coalis dried, which contaminates to remove during act 202 c) and predict theparameters of the stimulus applied to the coal. In one embodiment, thecharacteristics of the coal tar can be determined or predicted bysieving or otherwise determining the particle size of the coal (e.g.,the coal powder) prior to act 202 b. For example, coal exhibiting largerparticle sizes can take more time to be converted into coal tar and/orpredict the characteristics of the coal tar (e.g., whether the coal tarinclude non-coal tar components) formed during act 202 b. In oneembodiment, the characteristics of the coal tar can be determined orpredicted by subjecting the provided coal, the coal tar, and/or thedistilled coal tar to a thermogravimetric analysis (TGA) and/ordifferential scanning calorimetry (DSC”). It is noted that othertechniques can determine or predict the characteristics of the providedcoal, the coal tar, or the distilled coal tar other than other thoseprovided above.

In one embodiment, the evaluation can include determining thecharacteristics of the mesophase pitch after the coal tar was subjectedto the stimulus. Determining the characteristics of the mesophase pitchcan include using UV fluorescence, high-performance liquidchromatography, and/or mass spectroscopy. As previously discussed,determining the characteristics of the mesophase pitch can change theparameters of the stimulus applied to the coal tar to improve themesophase pitch formed. In one example, the changes to the parameters ofthe stimulus needed to improve the mesophase pitch based on the detectedcharacteristics of the mesophase pitch are known. In such an example,the parameters of the stimulus are merely changed to the knownparameters. In one example, the changes to the parameters of thestimulus needed to improve the mesophase pitch based on the detectedcharacteristics of the mesophase pitch are not known. In such anexample, one or more parameters of the stimulus applied to coal tar arechanged. The mesophase pitch formed from such coal tar is then tested todetermine if the characteristics of the mesophase pitch improved. Theparameters of the stimulus can remain unchanged if the characteristicsof the mesophase pitch improves a sufficient amount. However, one ormore parameters of the stimulus can be changed if the characteristics ofthe mesophase pitch did not improve a sufficient amount, remainedunchanged, or decreased.

The evaluation can include determining the characteristics of the spunfibers and/or the formed carbon fibers. For example, the evaluation caninclude determining the physical characteristics (e.g., tensilestrength, Young's modulus, etc.) of the spun fibers and/or the formedcarbon fibers using, for instance, an INSTRON machine.

In some examples, evaluating the effects of the stimulus on the coal tarduring a mesophase pitch formation processes can allow for theparameters of the stimulus to be selected to enhance certain reactionsduring the formation process and/or to produce mesophase pitch having acertain desired composition or certain desired properties, for exampleproperties that allow for the efficient production of high-qualitygraphene therefrom. In some examples where the stimulus comprises amagnetic field, the magnetic behavior of desired components of themesophase pitch can be evaluated and the parameters of the stimulus canbe selected in response. For example, it can be desirable for the pitchto include certain components, and the evaluation of the pitch after itis formed according to a stimulus having a first set of parameters canproviding information to allow the parameters of the stimulus to bemodified or selected to enhance one or more properties of the pitch.

In some examples, one or more properties of the pitch can be enhanced orcontrolled as desired by controlling the focus or location of thestimulus applied to the coal tar during the formation process. In someexamples, the application of the stimulus as a centered orgradient-based field can be controlled based on the evaluation of thepitch, coal tar, or products formed therefrom. In some examples, theheating of the coal tar caused by the stimulus can be evaluated. In someexamples, the local pressures of the coal tar caused by the stimulus canbe evaluated. In some examples, evaluation can allow for the selectionor modification of a processing temperature, as described with respectto FIG. 1 , that can desirably align oligomers present in the coal tarinto graphene-like aromatic structures in the subsequently formedmesophase pitch. In some examples, the parameters of the stimulus can beselected to form a pitch having a desired composition, such as includingaromatic molecules like triphenylene, coronene, or any other type ofdesired molecule or component. In some examples, the desired componentscan be desired precursors for the formation of carbon products, such ascarbon fibers or graphene, from the resultant pitch.

In some examples, the process steps described herein with respect toFIGS. 1 and 2 can efficiently produce mesophase pitch of a desiredquality and composition from coal tar using temperatures that are lowenough, and durations that are short enough to allow for the processesto be run in a continuous reactor. That is, any of the methods 100, 200described herein can be continuously operated in one or more reactors orreaction vessels to produce a continuous output of mesophase pitchhaving desired properties from a continuous input of coal tar, coal, orother coal-derived precursor. In some examples, the parameters of thestimulus can be modified as described herein while the continuousprocess is occurring or being carried out. For example, the coal tarand/or resultant pitch can be continuously evaluated as part of acontinuous reaction process and the stimulus, as well as other processparameters such as temperature or time, can be adjusted on the flyduring the continuous reaction process. This ability to continuouslymonitor and adjust reaction and stimulus parameters during a continuousreaction process can allow for the continuous formation of mesophasepitch having desired properties while accounting for variations in thequality of the incoming coal tar or other coal-derived feedstock. Thiswould, in turn, reduce the cost of the mesophase pitch by an order ofmagnitude, thereby significantly reducing the cost of carbon productsformed therefrom.

FIGS. 3A and 3B show two sample mass spectrographs of mesophase pitch.Each mass spectrograph shows the molecular weight in Daltons (Da) of thecomponents of the pitch along the X-axis and the relative intensity ofthe spectra along the Y-axis. A higher relative intensity indicates arelatively higher amount of components of the pitch having a certainmolecular weight. The mass spectrograph shown in FIG. 3A was taken froma sample of mesophase pitch produced according to the processesdescribed herein. In this particular example, coal tar was heated toabout 200° C. and a stimulus comprising a magnetic field having a fieldstrength of about 9 T was applied to the coal tar during the pitchformation process. As can be seen, there are six distinct peaks in themass spectrograph, indicating that the coal tar was polymerized intospecific components or molecules (each of which has a distinct molecularweight) while essentially no cracking of the monomers present in thecoal tar has occurred. This result is indicative of a mesophase pitchhaving select components at high purity levels, with little to noadditional components or molecules therein.

Specifically, the results show that there is little to nofractionalization or methylation of the molecules in the pitch. Withoutwishing to be bound by any one theory, it is believed that thisnon-methylated pitch will yield a more graphitic structure whengraphitized, thus improving the properties of the products requiring agraphitic structure. In contrast, the mass spectrograph shown in FIG. 3Bincludes a larger number of peaks at various molecular weights, as wellas significant broadening of the peaks, and multiple sub-peaks disposedbetween each of the relatively more intense primary peaks. These resultsare indicative of a pitch that includes a much larger variety ofcomponent molecules at a variety of concentrations, some of which may beundesirable for the subsequent formation of carbon products from thepitch. Additionally, the presence of multiple smaller and broader peaksis indicative of a significant amount of cracking of the monomers of theprecursor coal tar. The cracking of these monomers and the presence ofundesirable components in the pitch means that this pitch will be lessefficient at forming graphene or other carbon products as compared tothe pitch analyzed in the mass spectrograph of FIG. 3A. That is, theresultant graphene yield of the pitch analyzed in the mass spectrographof FIG. 3B will be significantly lower than the graphene yield of thepitch analyzed in the mass spectrograph of FIG. 3A, The pitch analyzedin the mass spectrograph of FIG. 3B was formed by conventional methodsthat do not include the application of a stimulus and at a temperatureof 400° C. Thus, even with a much higher processing temperature,conventional methods still result in the formation of pitch that doesnot have desired properties as compared to pitch formed according to theprocesses described herein.

Various inventions have been described herein with reference to certainspecific embodiments and examples. However, they will be recognized bythose skilled in the art that many variations are possible withoutdeparting from the scope and spirit of the inventions disclosed herein,in that those inventions set forth in the claims below are intended tocover all variations and modifications of the inventions disclosedwithout departing from the spirit of the inventions. The terms“including:” and “having” come as used in the specification and claimsshall have the same meaning as the term “comprising.”

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not target to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. A method for forming mesophase pitch, comprising:continuously providing coal tar to a reactor; applying a stimulus to anamount of the coal tar, the stimulus selected from the group consistingof at least one of an electromagnetic field (“EMF”) or a magnetic field,wherein applying the stimulus to the amount of coal tar heats the amountof coal tar to a temperature of from about 100° C. to about 300° C.; andcontinuously forming mesophase pitch from the coal tar.
 2. The method ofclaim 1, further comprising forming the amount of coal tar by at leastone of: reducing a particle size of an amount of coal to form coalpowder; sieving the coal powder; pyrolyzing the amount of coal andextracting the amount of coal tar from the pyrolyzed coal; or distillingthe amount of coal tar to remove one or more contaminants therefrom. 3.The method of claim 1, wherein the stimulus comprises the EMF.
 4. Themethod of claim 3, wherein the EMF has a wavelength of from about 1 mmto about 1 m.
 5. The method of claim 3, wherein the EMF comprises apulsed EMF.
 6. The method of claim 3, wherein applying the stimulus tothe amount of coal tar comprises: applying a first EMF to the amount ofcoal tar, the first EMF having a first property; and applying a secondEMF to the amount of coal tar, the second EMF having a second propertythat is different from the first property.
 7. The method of claim 1,wherein the stimulus comprises the magnetic field.
 8. The method ofclaim 7, wherein applying the stimulus to the amount of coal tarcomprises varying a magnetic field strength of the magnetic field. 9.The method of claim 1, further comprising: evaluating a characteristicof the amount of coal tar or the mesophase pitch; and changing aparameter of the stimulus applied to the amount coal tar in response toevaluating the characteristic of the amount of coal tar or the mesophasepitch.
 10. The method of claim 1, further comprising forming themesophase pitch into graphene, fullerene, diamond, or carbon fibers. 11.The method of claim 1, further comprising air blowing the mesophasepitch.
 12. The method of claim 1, further comprising subjecting themesophase pitch to a thermal process.
 13. A method for processing coaltar, comprising: evaluating a characteristic of an amount of coal or anamount of coal tar formed from the amount of coal; selecting one or moreparameters of a stimulus in response to evaluating the characteristic;and applying a stimulus having the one or more parameters to the amountof coal tar to form mesophase pitch, the stimulus selected from thegroup consisting of at least one of an electromagnetic field (“EMF”) ora magnetic field, wherein applying the stimulus to the amount of coaltar heats the amount of coal tar to a temperature of from about 100° C.to about 300° C.
 14. The method of claim 13, wherein: the stimuluscomprises the EMF; and selecting one or more parameters of the stimuluscomprises selecting from the group consisting of at least one of awavelength, an intensity, or mode of the EMF.
 15. The method of claim14, wherein the EMF has a wavelength of from about 1 mm to about 1 m.16. The method of claim 13, wherein: the stimulus comprises the magneticfield; and selecting one or more parameters of the stimulus comprisesselecting from the group consisting of at least one of a magnetic fieldstrength or mode of the magnetic field.
 17. A method for formingmesophase pitch, comprising: applying a stimulus to a first amount ofcoal tar to form a first amount of mesophase pitch, the stimulusselected from the group consisting of at least one of an electromagneticfield (“EMF”) or a magnetic field, wherein applying the stimulus to theamount of coal tar heats the amount of coal tar to a temperature of fromabout 100° C. to about 300° C.; evaluating a characteristic of the firstamount of mesophase pitch; changing a parameter of the stimulus inresponse to evaluating the characteristic of the first amount ofmesophase pitch; and applying the stimulus exhibiting the changedparameters to a second amount of coal tar to form a second amount ofmesophase pitch.
 18. The method of claim 17, wherein: the stimuluscomprises the EMF; and the parameter of the stimulus consists of atleast one of a wavelength, an intensity, or mode of the EMF.
 19. Themethod of claim 17, wherein: the stimulus comprises a magnetic field;and the parameter of the stimulus consists of at least one of a magneticfield strength or mode of the magnetic field.